Impacts. We aim to improve the mental health, family functioning, and well-being of veterans with posttraumatic stress disorder (PTSD) through developing and evaluating a trauma-focused, couple therapy for PTSD. We will use strategies from Integrative Behavioral Couple Therapy (ICBT) to help intimate partners support veterans during exposure therapy for PTSD (Prolonged Exposure; PE). We anticipate this approach will increase veterans? engagement in PE, but also improve relationship functioning, family functioning, and social functioning. Family involvement has been highlighted as a fertile avenue for improving the outcomes for patients with PTSD, yet families are infrequently integrated into evidence-based psychotherapies (EBPs). Our goals are highly is consistent with RR&D?s mission to promote research that leverages family support as a pathway to reintegration and optimizes meaningful recovery and functioning. Background. PTSD occurs in as many as 17% of US military veterans and is associated with a host of negative, long-term consequences to the individual, their families, and society at large. EBPs, such as PE, result in clinically significant symptom relief for many. Yet, these therapies have proven less effective for military personnel and veterans and treatment dropout rates are high. Our team surveyed veterans initiating EBPs for PTSD and a family member across four VA medical centers (N = 598; Project HomeFront). We found that veterans were more than twice as likely to complete EBPs when loved ones encouraged them to confront distress and that veterans experienced greater treatment gains when they shared more with their loved ones about their treatment. A couples-based, exposure therapy for PTSD that integrates intimate partners into every session of PE could provide the opportunity to mobilize the whole household in the service of EBP engagement, while extending the goals of therapy beyond symptom reduction to family functioning. We anticipate this intervention will teach couples to embrace a lifestyle that supports confronting trauma-related distress, so the veteran and his/her family can achieve optimal functional outcomes. Objectives. We will complete stages 1A and 1B of the Stage Model of Treatment Development. Specifically, we will: (1) Expand our treatment outline using content experts and feedback from key stakeholders (veterans, intimate partners, providers, and VA mental health leadership). (2) Conduct a pilot open trial to assess (a) the acceptability of treatment components, structure, and materials, (b) the feasibility of the intervention (retention and intervention fidelity), and (c) the study approach (screening, recruitment, and assessment process). (3) Explore the preliminary effects of the intervention on select outcomes including overall functioning, mental health functioning, social functioning, family functioning, and potential mechanisms (social control, subjective norms, and the degree to which veterans rely on their partners for support). Methods: To accomplish Aim 1, we will expand the outline for the intervention into an initial treatment manual through meetings with content experts and stakeholder feedback. Next, we will develop fidelity checklists and revise the treatment manual through conducting the intervention with 2-3 couples. To accomplish Aims 2 and 3, we will evaluate the intervention in a non-randomized, open trial with 10 veterans diagnosed with PTSD and their intimate partners. Veterans will complete baseline and posttreatment structured diagnostic interviews. Both members of the couple will complete baseline surveys, posttreatment surveys, and posttreatment qualitative exit interviews. Using data obtained from the open trial, we will assess the intervention?s acceptability, feasibility, mechanisms, and outcomes. Upon completion of this proposal, we will be well positioned to apply for Merit funding for a randomized clinical trial (Stage 2 of the Stage Model of Treatment Development) of this innovative, exposure based, couple therapy.